Transformaciones de fases sólido-sólido en el sistema al-ni. parte II

Uno de los sistemas que pertenece a las superaleaciones es el de Aluminio-Níquel. El objetivo de este trabajo es profundizar el análisis de sus fases intermetálicas (FIs) de mayor contenido de Ni, a 1000 y 1170°C, las cuales poseen atractivas características tecnológicas y diversas aplicaciones a nivel industrial. El proceso de Unión por Transición de Fase Líquida (Transition Liquid Phase Bonding, TLPB) permite obtener uniones de alta estabilidad mecánica y térmica, resistentes a la corrosión, y la formación de capas intermetálicas (CIs)/FIs de buena adhesividad con el sustrato, mediante procesos de difusión-reacción. Las CIs de mayor contenido de Ni crecen consumiendo a las capas de mayor contenido de Al. La secuencia es Al/C1/C2/C3/C4/C5/Ni, siendo C1: Al3Ni, C2: Al3Ni2, C3: AlNi-rica en Al, C4: AlNi-pobre en Al y C5: AlNi3. Se realizaron estudios de morfología, cinética, composición química y comportamiento mecánico, utilizando técnicas de microscopía óptica, electrónica (SEM-EDS) y microdureza Vickers, en C3, C4 y C5 con extensos tratamientos térmicos (TT). La capa C3 presentó una morfología porosa, disminuyendo su espesor a costa de C4 y un acelerado crecimiento de C5. C4 evidenció a ambas temperaturas una morfología lisa y otra martensítica, donde C4-martensita se consumió en última instancia a costa de C5. A ambas temperaturas y extensos TT, creció una fase de morfología porosa que llamamos C5-Superior. Los resultados de composición química y de dureza evidenciaron que la misma, es similar a C5 y se correlaciona con AlNi3. El estudio cinético reportó que a 1000°C, las capas C4 y C5 tienen un crecimiento parabólico controlado por difusión. A 1170°C, C4 creció con un control por reacción en la interface, mientras que C5, cambió la modalidad parabólica de crecimiento cuando desapareció C3, incrementando sustancialmente su constante de crecimiento. Los valores de microdureza Vickers disminuyeron con el incremento del contenido de Ni, a ambas temperaturas.One of the systems belonging to the superalloys is Nickel/Aluminum. The aim of this work is to deepen the analysis of this superalloy’s inter-metallic phases (IPs) of higher Ni content, at 1000 and 1170°C, which have attractive technological characteristics and diverse industrial applications. The Transition Liquid Phase Bonding (TLPB) process allows obtaining joints with higher thermal and mechanical stability, corrosion resistance, and formation of inter-metallic layers (ILs)/IPs of good adhesion to the substrate through diffusion-reaction processes. The ILs with the highest Ni concentration grow by consuming the layers with the highest content of Al. The sequence is Al/L1/L2/L3/L4/L5/Ni, being L1: Al3Ni, L2: Al3Ni2, L3: AlNi(Al rich), L4: AlNi(Al poor) and L5: AlNi3. Morphology, kinetics, chemical composition and mechanical behavior studies were performed, using optical and electronic microscopy (SEM/EDS) and Vickers micro-hardness techniques in layers L3, L4 and L5 under extensive thermal treatments (TT). Layer L3 presented a porous morphology, decreasing its thickness at the expense of L4 and an accelerated growth of L5. L4 showed a smooth and a martensitic morphology at both temperatures, where L4-martensite was ultimately consumed at the expense of L5. A phase of porous morphology that we called L5- Superior, grew at both temperatures and extensive TT. The results of chemical composition and micro-hardness showed that it is similar to L5 and correlates with AlNi3 phase. The kinetic study reported that L4 and L5 exhibit parabolic growth, controlled by diffusion, at 1000 °C. L4 grew, controlled by interface reaction, at 1170°C, while L5 changed the parabolic growth when L3 disappeared, increasing its growth rate constant. Vickers micro-hardness values decreased with Ni concentration at both temperatures.Fil: Segobia, Sofía. Universidad Nacional del Comahue; ArgentinaFil: Sommadossi, Silvana Andrea. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; Argentin

Hot deformation behavior of a ni‐based superalloy with suppressed precipitation

Abstract:Inconel ® 718 is a well-known nickel-based super-alloy used for high-temperature applicationsafter thermomechanical processes followed by heat treatments. This work describes theevolution of the microstructure and the stresses during hot deformation of a prototype alloy namedIN718WP produced by powder metallurgy with similar chemical composition to the matrix ofInconel ® 718. Compression tests were performed by the thermomechanical simulator Gleeble3800 in a temperature range from 900 to 1025 °C, and strain rates scaled from 0.001 to 10 s. Flow curves of IN718WP showed similar features to those of Inconel ® 718. The relative stress softening of the IN718WP was comparable to standard alloy Inconel ® 718 for the highest strain rates. Large stress softening at low strain rates may be related to two phenomena: the fast recrystallization rate, and the coarsening of micropores driven by diffusion. Dynamic recrystallization grade and grain size were quantified using metallography. The recrystallization grade increased as the strain rate decreased, although showed less dependency on the temperature. Dynamic recrystallization occurred after the formation of deformation bands at strain rates above 0.1 s-1 and after the formation of subgrains when deforming at low strain rates. Recrystallized grains had a large number of sigma 3 boundaries, and their percentage increased with strain rate and temperature. The calculated apparent activation energy and strain rate exponent value were similar to those found for Inconel ® 718 when deforming above the solvus temperature.Keywords: ; hot deformation; Gleeble; recrystallization; flow modelling approachFil: Lizzi, Franco. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; Argentina. Christian Doppler Laboratory for Design of High-Performance Alloys by Thermomechanical Processing; AustriaFil: Pradeep, Kashyap. Graz University Of Technology.; Austria. Christian Doppler Laboratory for Design of High-Performance Alloys by Thermomechanical Processing; AustriaFil: Stanojevic, Aleksandar. Voestalpine Böhler Aerospace; AustriaFil: Sommadossi, Silvana Andrea. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Poletti, MARIA CECILIA. Christian Doppler Laboratory for Design of High-Performance Alloys by Thermomechanical Processing; Austria. Graz University Of Technology.; Austri

Dft-cef approach for the thermodynamic properties and volume of stable and metastable al–ni compounds

The Al–Ni system has been intensively studied both experimentally and theoretically. Previous first-principles calculations based on density-functional theory (DFT) typically investigate the stable phases of this system in their experimental stoichiometry. In this work, we present DFT calculations for the Al–Ni system that cover stable and metastable phases across the whole composition range for each phase. The considered metastable phases are relevant for applications as they are observed in engineering alloys based on Al–Ni. To model the Gibbs energies of solid phases of the Al–Ni system, we combine our DFT calculations with the compound energy formalism (CEF) that takes the Bragg–Williams–Gorsky approximation for the configurational entropy. Our results indicate that the majority of the investigated configurations have negative energy of formation with respect to Al fcc and Ni fcc. The calculated molar volumes for all investigated phases show negative deviations from Zen’s law. The thermodynamic properties at finite temperatures of individual phases allow one to predict the configurational contributions to the Gibbs energy. By applying a fully predictive approach without excess parameters, an acceptable topology of the DFT-based equilibrium phase diagram is obtained at low and intermediate temperatures. Further contributions can be added to improve the predictability of the method, such as phonons or going beyond the Bragg–Williams–Gorsky approximation that overestimates the stability range of the ordered phases. This is clearly demonstrated in the fcc order/disorder predicted metastable phase diagramFil: Tumminello, Silvana Deisy Paulina. Universidad Nacional del Comahue; Argentina. Universidad Nacional de San Martín; Argentina. Ruhr Universität Bochum; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Palumbo, Mauro. Ruhr Universität Bochum; AlemaniaFil: Koßmann, Jörg. Ruhr Universität Bochum; AlemaniaFil: Hammerschmidt, Thomas. Ruhr Universität Bochum; AlemaniaFil: Alonso, Paula Regina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; ArgentinaFil: Sommadossi, Silvana Andrea. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Fries, Suzana G. Ruhr Universität Bochum; Alemani

Untersuchungen zum Diffusionslöten in den Systemen Cu/In/Cu und Cu/In-48Sn/Cu

Das Diffusionslöten ist ein bleifreies Verbindungsverfahren, das ein großes Potential zur Lösung vieler moderner Verbindungsprobleme bietet. Sie bestehen darin, dass die Verbindungsstellen in der Mikroelektronik immer kleiner werden, zu immer höheren Temperaturen ausgesetzt werden, bei tieferen Temperaturen herstellbar und bleifrei sein sollen. Das Ziel dieser Arbeit war die Entwicklung eines Verbindungsverfahrens, bei dem die Verbindung zwischen verschiedenen Materialien durch intermetallische Phasen (IP) zustande kommt. Außerdem werden Konzepte über die Mehrkomponenten-diffusion vorgestellt, die als Designstrategie zur Verbesserung von Verbindungesverfahren dienen. Die Kennzeichnung der Cu/In/Cu und Cu/In-48Sn/Cu Verbindungen, die aus einem Diffusionslöten Prozess resultieren, wird dargestellt (Ni/Al/Ni als zusätzliches System). Die resultierenden Verbindungen bestehen somit völlig aus IP. Die entstehenden IP haben in der Regel einen viel höheren Schmelzpunkt als die „Löttemperatur“, bei der sie gebildet sind und halten deshalb Betriebstemperaturen aus, die höher sind als die Herstellungstemperatur! Sie verhalten sich somit konträr zu konventionellen Lötverbindungen, die schon 50-100°C unterhalb der Löttemperatur ihre Beständigkeit verlieren. Der Unterschied zwischen Herstellungs- und Betriebstemperatur kann -je nach Materialsystem- bis zu 400 und 600°C betragen. Das Diffusionslöten hat sogar die Vorteile des herkömmlichen Weichlötens, d.h., gute Füllung der Verbindung und niedrige Herstellungstemperatur, und aber gleichzeitig den großen Vorteil der hohen Betriebstemperatur. Für das Verständnis der Eigenschaften und der Grenzflächenreaktionen in Diffusionslötverbindungen, z.B. die Kenntnis der betreffenden Diffusionskoeffizienten und anderer kinetischer Parameter werden die folgenden Aspekte analysiert: Morphologie, Chemie, Kinetik; Mechanismus der Bildung der IP, Langzeitstabilität und Zusammenhang zwischen Struktur und Eigenschaften der Lötverbindung. Bei der Untersuchung wurden die Möglichkeiten der Licht- und Rasterelektronenmikroskopie (SEM), der Mikroanalyse (EPMA), Transmissionselektronenmikroskopie (TEM) und der Röntgenographie (XRD) genutzt. Die EPMA Untersuchungen ergeben dass die Reihenfolge von IP in Cu/In/Cu-Paaren einen zunehmenden Cu-Gehalt zeigen: Cu11In9 → Cu2In → Cu7In3 bei T 310 °C. In den Cu/In-48Sn/Cu-Paaren entwickeln sich zwei Schichten von IP mit folgenden Durchschnittsgehalten (At.%): Cu-16In-27Sn und Cu-10In-13Sn, die den eta- und dseta-Regionen im Zustandsdiagramm Cu-In-Sn entsprechen. Unterhalb von 200 °C wird nur die eta-Phase in der Verbindungszone gebildet. Die kinetischen Untersuchungen des Wachstums der IP zeigte sich im Cu/In/Cu-System als volumendiffusionskontrolliert und im Cu/In-Sn/Cu-System als reaktionskontrolliert. Die dseta-Phase von die Cu/In-48Sn/Cu-Paaren wächst viel schneller als die Schichten in den binären Cu/In/Cu-Diffusionspaaren. Die Diffusionskoeffiziente für das volumendiffusionskontrollierte Wachstum und die Aktivierungsenergie für den Phasenwachstumsprozess wurden berechnet. Das mechanische Verhalten einer Verbindung ist ein wichtiger Aspekt seiner Zuverlässigkeit. Deshalb wurden neben die Temperaturbeständigkeit und der Härte, die Zug- und Scherfestigkeit auch nach thermischen Zyklen bestimmt und zusammen mit fraktographischen Analysen (SEM) interpretiert. Die Experimente zur Temperaturbeständigkeit zeigten, dass die Cu/In/Cu-Proben bis 650°C und die Cu/In-Sn/Cu-Proben bis etwa 750°C beständig sind. Damit sind die Verbindungen noch über 400°C oberhalb der Herstellungstemperatur (250-290°C) beständig. Es zeigte sich, dass die Cu/In-Sn/Cu-Verbindungen fester sind als die Cu/In/Cu-Verbindungen und ein schnelles Wachstum von IP haben. Deswegen wurden nur die mechanischen Eigenschaften der Cu/In-Sn/Cu-Verbindungen in Detail untersucht. Wenn die Verbindungszone eine eta-Schicht enthält (alleine oder zusammen mit einer dseta-Schicht), tritt der Bruch in der eta-Schicht auf. Die Bruchfestigkeitswerte in den Zug- und Scherversuchen waren in diesen Fällen niedrig. Wenn nur die dseta-Phase anwesend war, wurden bessere mechanische Eigenschaften beobachtet. Die Bruchfestigkeitswerte in den Versuchen erhöhten sich drastisch, wenn die eta-Phase vollständig in die ζ-Phase umwandelt war. Die Scher- und Zugversuche zeigten Bruchfestigkeitswerte von etwa 150 MPa. Die Härtewerte der eta- und dseta-Schichten waren ungefähr 4- bzw. 3mal höher als die von Cu. Folglich war die eta-Schicht spröder als die dseta-Schicht. Außerdem wurde die doppelte Kristallisationsmorphologie der eta-Phase durch zwei unterschiedliche Härtewerte hervorgehoben. Diese Härte-Ergebnisse sind im Einklang mit den Zug- und Scherversuchen, die zeigten, dass die eta-Phase die schwächste intermetallische Phase in den Verbindungen ist.The diffusion soldering is a lead-free interconnection technology, which offers a large potential for the solution of many modern joining problems. These problems can be explained in the following way: in microelectronics the bonds become thinner, higher service temperatures have to be resisted, lower process temperatures and lead-free solders are required. The goal of this work was the development of a joining process, the diffusion soldering, which is able to connect different materials through intermetallic phases (IP) in the interconnection zone. Additionally, multicomponent diffusion concepts as presented here provide design strategies to improve the performance of bonding techniques. The characterization of the Cu/In/Cu and Cu/In-48Sn/Cu joints resulting from a diffusion soldering process is presented (Ni/Al/Ni as additional system). The resulting bond is suited to applications at service temperatures much higher than the low manufacture temperature because the interconnection zone consists of solid IP. Diffusion soldered joints behave contrarily to conventional soldered joints, which already lose their stability 50 to 100°C below the soldering temperature. The difference between process and service temperature, which depends on the material system, can be around 400 to 600°C. The diffusion soldering has even the advantages of the conventional soft soldering, i.e. good filling of the joint geometry and low manufacture temperature, and additionally offers the large advantage of a high service temperature. Further advantage of this technique is a small joint volume. For the understanding of the bond properties and the process involved in diffusion soldering as diffusion, interface reactions, etc., the following aspects were analyzed: morphology, chemistry, kinetics and mechanism of formation of the IP; in order to obtain interdiffusion coefficients, kinetic parameters and relations between structure and characteristics of the joint. During the investigations optical and scanning electron microscopy (SEM), the electron probe microanalysis (EPMA), transmission electron microscopy (TEM) and the X-ray diffraction analyses (XRD) were used. The EPMA investigations revealed that the sequence of appearance of the IP in Cu/In/Cu couples shows an increasing Cu content according to the Cu-In phase diagram: Cu11In9, CuIn2, Cu7In3 at T 310 °C. In the Cu/In-48Sn/Cu couples two IP layers developed with the following average compositions (At.%): Cu-16In-27Sn and Cu-10In-13Sn, which correspond to eta- and dseta-regions in the Cu-In-Sn phase diagram. Below 200 °C only the eta-phase is formed in the interconnecting zone. The kinetic investigation of the IP growth has shown that in the Cu/In/Cu system the layer growth is controlled by volume diffusion and in the Cu/In-48Sn/Cu system is controlled by reaction at the interface. The dseta-phase of the Cu/In-48Sn/Cu couples grows much faster than the IP layers of the binary Cu/In/Cu couples. Additionally, the diffusion coefficients for volume diffusion-controlled growth and the activation energy for the IP growth process for both systems were calculated. The mechanical behaviour of a joint is an important aspect of its reliability. Therefore, temperature stability and hardness measurement, tensile and shear testing, also after thermal cycles, were performed. The shear, tensile and hardness values were interpreted together with fractographic analysis (SEM) in order to determine the fracture mode. The temperature stability experiments have shown that the Cu/In/Cu and Cu/In-48Sn/Cu bonds can withstand service temperatures up to 650°C and 750°C, respectively. Thus the joints are still stable over 400°C above the manufacture temperature (250-290°C). Only the mechanical properties of the Cu/In-48Sn/Cu bonds were examined in detail. If the interconnection zone contains a eta-layer (alone or together with dseta-layers), the fracture arises through the eta-layer. The tensile and shear strength values are low in these cases. If only the dseta-phase was present in the bond region, better mechanical characteristics were observed. If the eta-phase converts completely into the dseta-phase, the tensile and shear strength values increase drastically, showing values of 150 MPa approximately. The hardness values of eta- and dseta-layer are approximately 4 and 3 times higher than for Cu substrate, respectively. Therefore, the eta-layer seems to be more brittle than the dseta-layer. In addition, the double crystallization morphology of the eta-phase is emphasized by two different hardness values over this layer. These hardness results are in good agreement with the tensile and shear strength values, which indicate that the eta-phase is the weakest IP in the interconnection zone

Estudio termodinámico y cinético de sistemas intermetálicos multicapas en uniones libres de plomo

Este trabajo de investigación se centra en el estudio termodinámico de aleaciones multicomponentes abordado desde dos enfoques, cada vez más complementarios: predictivo y empírico. El primero predice propiedades macroscópicas partiendo desde la estructura fundamental de la materia, mientras que, el segundo parte desde la evidencia empírica para dar sentido a sus modelos teóricos. El objetivo final es marcar la complementariedad y las limitaciones aún por resolver para una combinación consistente de ambos enfoques.El estudio termodinámico de dos sistemas multicomponentes, Al-Ni y Cu-In-Sn, se realizó coordinando actividades experimentales y teóricas de carácter complementario en el desarrollo o validación de modelos. Los antecedentes de cada sistema y las limitaciones encontradas en cada enfoque motivaron a tratar en esta tesis y buscar respuestas a ciertas cuestiones como: -buscar una base de datos termodinámica compatible con determinaciones experimentales realizadas en nuestro grupo y abierta que admita modificaciones y optimización de los modelos.-utilizando el sistema Al-Ni, para el cual existe un diagrama de equilibrio bien determinado, es posible predecir el equilibrio y las propiedades de las fases únicamente con propiedades calculadas de primeros principios?, cuán cerca del diagrama de fases aceptado se puede llegar?.-Es conveniente ajustar propiedades calculadas con alta precisión para su utilización en el entorno de CALPHAD?, se evalúa la posibilidad de una entrada más conveniente para este tipo de datos.-Es factible incorporar propiedades calculadas de primeros principios en la descripción del ternario Cu-In-Sn?, cómo se incorporar consistentemente propiedades con estados de referencia distintos?.Fil: Tumminello, Silvana Deisy Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Instituto Sabato; ArgentinaFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Paula Regina. Comisión Nacional de Energía Atómica; Argentin

Characterization of Al-Ni intermetallics around 30-60 at% Al for TLPB application

Interest on the Al–Ni equilibrium diagram along the latest years is associated with the attractive properties of its intermetallic phases, such as high thermal stability, high corrosion resistance and high strength to density ratio. The Transient Liquid Phase Bonding (TLPB) is a technological process which can be applied to manufacture new pieces and to perform reparations. Morphology, composition profiles, growth kinetic and hardness as a function of temperature and composition of the Intermetallic Layers (ILs) were analyzed, especially focused on solid–solid interactions during isothermal annealing in reactive diffusion couples Ni/Al (800–1170 °C). The study yields to the following association of the Al–Ni Intermetallic Phases (IPs) to the ILs: L1 (Al3Ni), L2 (Al3Ni2), L3 (Ni-poor AlNi), L4 (Ni-rich AlNi) and L5 (AlNi3). The composition ranges of L3 and L4 are 36–46 and 53–58 at% Al, respectively. Martensitic transformation was found in the half thickness of L4 (L4M and L4S) at 1170 °C. Kinetics show diffusion controlled growth for L2 and L5 and interface reaction control for L4 at 800–1170 °C, while L3 revealed a mixed kinetic behavior: parabolic at 800–1000 °C and linear at 1170 °C. The growth rate constants presented temperature dependence according to the Arrhenius model. Vickers microhardness values decrease with annealing temperature and Ni concentration for ILs, and put in evidence different mechanical properties of L3, L4M and L4S.Fil: Urrutia, Guillermo Alejandro. Universidad Nacional del Comahue; ArgentinaFil: Tumminello, Silvana Deisy Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. IDEPA - Subsede San Antonio Oeste; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Aricó, Sergio Fabián. Comision Nacional de Energia Atomica. Centro Atomico Constituyentes. Departamento de Materiales; ArgentinaFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. IDEPA - Subsede San Antonio Oeste; Argentina. Universidad Nacional del Comahue; Argentin

Microstructure Evolution and Phase Identification in Ni-Based Superalloy Bonded by Transient Liquid Phase Bonding

This study investigates the development of the microstructure in the interconnection zone of an IN718/Al/IN718 couple obtained by the Transient Liquid Phase Bonding (TLPB) process at 1000 °C. The crystal structure, composition and orientation of the phases formed during joining were examined by SEM-EDS EBSD. The results showed that the interconnection zone is a multilayered region, constituted mainly by sigma (σ), Laves and α-Cr phases and the AlNi intermetallic. The evolution of the microstructure over time shows that the topologically close-packed (TCP) phases grow as columnar grains, while the AlNi phase forms exiaquied grains. The AlNi phase is split into two layers, Al-rich and Ni-rich, both having the same crystal structure but different chemical composition. EBSD mapping revealed that there is no grain boundary along the split line, suggesting that splitting results from a solid-state transformation requiring no nucleation. At longer bonding time, the AlNi phase is enriched in Ni and presents nanoprecipitates homogeneosly dispersed. These results provide experimental data that contribute to the understanding of TLPB of superalloys.Fil: Poliserpi, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Buzolin, Ricardo. Graz University Of Technology. Maschinenbau Und Wirtschaftswissenschaften. Institut Fur Werkstoffkunde Fugetechnik Und Umformtechnik.; AustriaFil: Boeri, Roberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Poletti, Cecilia. Graz University Of Technology. Maschinenbau Und Wirtschaftswissenschaften. Institut Fur Werkstoffkunde Fugetechnik Und Umformtechnik.; AustriaFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; Argentin

Analysis of Splitting and Martensitic Transformation of AlNi Intermetallic Obtained by Transient Liquid Phase Bonding

This study investigates the characteristics of the AlNi intermetallic formed in a Ni/Al/Ni couple obtained by the Transient Liquid Phase Bonding (TLPB) process. The crystal structure and orientation of the AlNi intermetallic phase were evaluated through SEM-EDS EBSD and its mechanical properties were analyzed by means of instrumented hardness. The results showed that AlNi intermetallic splits into two layers, with different Al content and the same crystal structure and orientation. EBSD mapping revealed that there is no grain boundary along the split line, suggesting that a chemical partition takes place without the need of nucleation, like in a spinodal decomposition. A martensitic layer formed at the Ni-rich AlNi split side was identified by indexing the measured Kikuchi patterns. Instrumented hardness showed that the mechanical properties of AlNi phase change markedly depending on its chemical composition. These results provide experimental data that contribute to the understanding of the solid-state transformations occurring in the central portion of the Al-Ni phase diagram under isothermal conditions.Fil: Poliserpi, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Buzolin, Ricardo. Graz University Of Technology.; AustriaFil: Boeri, Roberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Poletti, MARIA CECILIA. Graz University Of Technology.; AustriaFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería. Universidad Nacional del Comahue. Instituto de Investigación En Tecnologías y Ciencias de la Ingeniería; Argentin

Multiphase Characterization of Cu-In-Sn Alloys with 17 at.% Cu and Comparison with Calculated Phase Equilibria

Cu-In-Sn alloys are among the suggested materials to replace Pb-Sn alloys traditionally used in joining processes by the electronic industry. Thorough thermodynamic understanding is required for the selection/design of adequate and efficient alloys for specific applications. Understanding the effects that high cost elements such as In have on microstructure and phase stability is imperative for industrial use. In this work ternary alloys were prepared by melting high purity elements (5N) for selected compositions of the 17 at.% Cu isopleth, and cooling down to reproduce process conditions. Chemical composition was determined using scanning electron microscopy equipped with electron probe microanalysis. Measurements of transition temperatures were done by heat-flux differential scanning calorimetry. We present a comprehensive comparison between our experimental results and phase diagram calculations using Liu et al. (J Electron Mater 30:1093, 2001) thermodynamic description based in the CALPHAD method, available in the literature.Fil: Tumminello, Silvana Deisy Paulina. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería; ArgentinaFil: Del Negro, N.. No especifica

Crystallographic characterization of Cu-In alloys in the 30-37 at.% In region

The Cu-In-Sn system is one of the Pb-free options to replace conventional Pb-Sn alloys in electronic industry. However, controversies still exist regarding some regions of the equilibrium phase diagram of the Cu-In-Sn ternary and also of the Cu-In and Cu-Sn binary systems. One of the most controversial fields of the Cu-In binary phase diagram lies between ~33 and 38 at.% In and temperatures ranging from 100 up to 500 °C. In this work, binary Cu-In alloys, with 30-37 at.% In nominal compositions and annealed at two different temperatures (i.e. 300°C and 500°C) for a long period (i.e. 7 months) were characterized by scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS) and X-ray diffraction (XRD). Three phases exist over the 33-38 at.% In composition range, namely the phase A at high temperatures and the B and C phases at low temperatures. These three phases can be described as superstructures of the hexagonal phase h (Cu2In) and differ, although slightly, from those previously reported in the literature. In addition, it has been demonstrated that even conventional XRD allows to unequivocally distinguishing between these phases despite their similar crystal structure.Fil: Baque, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Torrado, D.. Universidad Nacional del Comahue. Facultad de Ingeniería; ArgentinaFil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería; ArgentinaFil: Aricó, Sergio Fabián. Comisión Nacional de Energía Atómica; ArgentinaFil: Craievich, A.F.. Universidade de Sao Paulo; BrasilFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentin